Dubnium was discovered by workers at the Nuclear Institute at Dubna (RU) and by workers at the University of California, Berkeley (US) in 1967. The origin of the name dubnium is the Joint Nuclear Institute at Dubna, Russia, an institute heavily involved in the search for heavy elements. It is a synthetic radioactive metal. Dubnium was made by bombarding californium-249 with a beam of nitrogen-15 ions. There are now five known isotopes of dubnium. The longest-lived is dubnium-262, with a half-life of 34 seconds.